Question

What type of reaction takes place between the Grignard reagent and the carbonyl compound? A. \(\mathrm{S}_{\mathrm{N}} 1\) B. \(\mathrm{S}_{N^2}\) C. nucleophilic addition D. bimolecular elimination

Short answer

C. nucleophilic addition

Step-by-step solution

Understand the Reactants

Identify the Grignard reagent (an organomagnesium halide) and the carbonyl compound (such as aldehyde or ketone).

Identify the Reaction Type

Recognize that Grignard reagents react with carbonyl compounds involving the nucleophilic addition of the Grignard reagent to the carbonyl carbon.

Analyze the Mechanism

Understand the mechanism: the nucleophile (R-MgX from the Grignard reagent) attacks the electrophilic carbon of the carbonyl group, forming an alkoxide intermediate which is then protonated to give an alcohol.

Choose the Correct Answer

From the options provided, identify option C (nucleophilic addition) as the correct description of the reaction mechanism.

Key concepts

nucleophilic addition

Nucleophilic addition is a fundamental chemical reaction where a nucleophile adds to an electrophile. In the context of Grignard reagents, this involves the nucleophile (organomagnesium halide) attacking the electrophilic carbon in a carbonyl compound.
The basic steps are:

• The nucleophile approaches the electrophile.
• The nucleophile donates electrons to form a new bond.
• An intermediate is formed, which is usually protonated to give the final product.

This type of reaction is crucial in organic chemistry because it forms new carbon-carbon bonds, leading to the synthesis of alcohols when working with carbonyl compounds.

organomagnesium halide

An organomagnesium halide, commonly known as a Grignard reagent, is created when an alkyl, vinyl, or aryl halide reacts with magnesium in an anhydrous ether solvent. These reagents are highly reactive due to the polar nature of the carbon-magnesium bond.
Here are a few key points:

• The carbon atom in the Grignard reagent is nucleophilic.
• It readily attacks electrophiles like the carbonyl carbon in aldehydes or ketones.
• The Grignard reagent must be prepared and handled under anhydrous conditions, as it reacts violently with water.

Understanding the behavior of organomagnesium halides is essential for anyone delving into synthetic organic chemistry.

carbonyl compound

A carbonyl compound features a carbon-oxygen double bond, making the carbon atom electrophilic. Common carbonyl compounds include aldehydes and ketones.
A few essential characteristics include:

• The carbonyl carbon is an electrophile, making it susceptible to nucleophilic attack.
• The oxygen in the carbonyl group has a partial negative charge due to its high electronegativity.
• When a nucleophile, like a Grignard reagent, attacks the carbonyl carbon, it breaks the double bond, leading to the formation of an alkoxide intermediate.

The reactivity of carbonyl compounds is pivotal in organic synthesis, as it opens pathways to forming various products.

reaction mechanisms

Understanding reaction mechanisms is vital in mastering organic chemistry. It involves breaking down the sequence of steps that occur during a chemical reaction.
For the reaction between a Grignard reagent and a carbonyl compound, the mechanism can be summarized as:

• The Grignard reagent (nucleophile) attacks the carbonyl carbon (electrophile).
• Bond formation occurs between the nucleophile and the electrophile, resulting in an alkoxide intermediate.
• The intermediate is then protonated, usually during a workup step, converting it into an alcohol.

Recognizing and visualizing these steps helps in predicting and controlling the outcome of chemical reactions, essential for efficient synthetic strategies.